When expending operational tasks in production, increasing of production process efficiency plays an important role. It can be achieved in particular due to fast and accurate object positioning at different periods of time within the production facilities. Effective monitoring of object movements allows creating an exact map of the production process, for example, at nighttime, and thereby reducing the number of employees involved.
Known methods for measuring of object displacement are based on the displacement of a transducer and a signal source with respect to each other. For example, in digital systems a signal from the source is processed to obtain a value of a moving object only if the transducer received it. Thus, the accuracy of object position detection depends on the value of the measuring range of transducers, which in turn depends on and is limited to the area of the transducer sensitivity.
A known method for measuring of object displacement (JP0850004, 20 Feb. 1996) consists of the following: the signal source—a magnet—is installed on the object; along the path of its movement the transducers—Hall sensors—are arranged. The exciting current is applied to the transducers. When an object is in motion, the voltage values are taken from the Hall sensors and then the value of the object movements are calculated.
The disadvantages of this method are the low accuracy of measuring and limited measurement range due to transducers sensitivity area. In addition, it is necessary to lay an electric cable to each of the Hall sensor to ensure its supply and signal pickup. Thus, it considerably complicates the measurement system.
There are known methods for measuring of object displacement (RU2125235, 20 Jan. 1999, RU2117914, 20 Aug. 1998), according to which the transducer is installed on a movable object, the ultrasonic waves propagate from the sources located along the path of the object. One measures the signal propagation time from the source to the transducers and this value is used to estimate the value of the linear movement of the object.
The disadvantage of these methods is the inability to measure the object position outside the area of transducer sensitivity that does not allow to measure movement of the object to considerable distances, and thereby limits the use in production.
There is a known method for measuring of object displacement (RU2196300, 10 Jan. 2003), according to which the transducer—a photoelectric receiver is installed on a moving object; using an optical system a light signal is fed to the transducer from the sources located along the path of the object, the photoelectric receivers use the output signal to estimate the value of object movement.
The disadvantage of this method is the low accuracy, as far as the value of object movement depends on the location, size and intensity of the light spot on the photoelectric receiver. Using this method it is impossible to measure the object movement at a considerable distance. Moreover implementation of the method requires the additional equipment to be used (the optical system, the additional photoelectric receiver to account for the light flow instabilities of the emitter) that causes inconvenience in use and leads to additional expenses for object positioning.
There is a known method of determining the absolute displacement of objects (RU93003536, 10 Aug. 1995), according to which the mask and the measuring scale have a few rows of identical slots so that periods of slot arrangement have no common dividers. The mask is placed on the movable object, the measurement scale is set along the path of the object; by passing of the object with the mask along the measuring scale the intensity of light passing through the slots of the mask and the measuring scale is changed with a predetermined period, and values of the period fractions for each row have no common integer dividers, and thus the absolute value of moving object is determined.
This method makes it possible in theory to increase the measuring range of object positioning due to unique periods of the mask and the measuring scale in any period of time. However, the application of dividers on the mask and the measuring scale is time-consuming and inconvenient; thus, virtually measuring the object displacement at a considerable distance is not possible. In addition, the accuracy of movement determination depends on the intensity of light spots produced after passing through the mask slots. In this connection the accuracy is low.
There is a known method for measuring of object displacement (RU1820209, 7 Jun. 1993), taken as the closest analog to the subject method. It consists of the following: the transducer—a photosensitive charge-coupled device—is installed on a movable object. Along the path of the object movement there are signal sources—the illuminating line, the signals—rays of light—are formed and the distance between them is less than the transducer length. Cyclic polling of the transducer is put into effect. The signal sources are switched on in a predetermined sequence, one for each polling cycle of the transducer. When receiving the output signal, exhaustive search for switching on the signal sources is stopped, the output signal is converted, the signal source number is determined, and due to it the movement of an object is determined as well.
This method allows increasing the measured distance at which the object can be moved. However, in this case, till the appearance of the output signal, overall time for determining the value of object movement increases due to exhaustive search for switching signal sources. In this method as well as in the analogs measurement accuracy is dependent on the area of the transducer sensitivity.